The present invention relates to soil (or sand) compacting machines and, more particularly, to machines for compacting soil in trenches around and under pipes, such as sewer pipes and water mains.
Trenches are frequently dug in roadways in conjunction with pipe installations. Then the pipe is laid in the trench. As fill material (soil or sand) is subsequently replaced into the trench, it must somehow be compacted around and under the pipe. Present soil compacting machines fail to compact the soil under the pipe "haunches" and up to the "spring line" of the pipe. The "spring line" is the a hypothetical centerline of the pipe, above which is the top portion of the pipe, below which is the bottom portion of the pipe. The "haunch" is a portion of the bottom portion of the pipe, below the spring line.
Construction codes often require that the soil or sand surrounding a pipe meet soil compacting specifications of 95% Proctor. The term "Proctor" refers to the density of the soil or sand from a particular sample. If the soil is inadequately compacted under the haunches of the pipe, rising water tables are likely to cause soil runoff under the haunch of the pipe which, in turn, causes both the pipe and the street above the pipe to settle and, in some cases, causes the pipe to break. This creates an undesirable sinkhole in the street which is extremely costly to repair, and a very dangerous condition to the public. Failures of this type have been know to cause entire sections of roadway to collapse.
In the past, soil around pipes has been compacted primarily through the use of jack hammers (with ram plate ends attached thereto), or the like. Such "manual" techniques are not only time consuming and expensive, the results obtained thereby are often marginal, at best. The jackhammer operator must stand astride the pipe, between the pipe and the trench wall. In the event that the trench wall caves in, the operator can be crushed between the trench wall and the pipe.
U.S. Pat. No. 3,814,533, incorporated by reference herein, discloses a soil compactor which uses eccentric weights to compact the soil. The compactor of this patent is useful for compacting small areas of soil in a downward, vertical direction.
U.S. Pat. No. 3,737,244, incorporated by reference herein, discloses a soil compactor which is pulled by a tractor or the like, which is useful for compacting soil in a downward, vertical direction.
The prior art is lacking in teachings directed to compacting soil under the haunches of pipes in trenches.